Search Publications
High Dense Gas Fraction in Intensely Star-forming Dusty Galaxies
Ivison, R. J.; Omont, A.; Bremer, M. +20 more
We present ALMA J=3{--}2 and VLA J=1{--}0 observations of the dense molecular gas tracers HCN, HCO+, and HNC in two lensed, high-redshift starbursts selected from the Herschel-ATLAS survey: H-ATLAS J090740.0-004200 (SDP.9, {z}{spec}=1.575) and H-ATLAS J091043.1-000321 (SDP.11, {z}{spec}=1.786). In SDP.9 we have det…
Test of Parameterized Post-Newtonian Gravity with Galaxy-scale Strong Lensing Systems
Li, Xiaolei; Cai, Yongzhi; Cao, Shuo +3 more
Based on a mass-selected sample of galaxy-scale strong gravitational lenses from the SLACS, BELLS, LSD, and SL2S surveys and using a well-motivated fiducial set of lens-galaxy parameters, we tested the weak-field metric on kiloparsec scales and found a constraint on the post-Newtonian parameter γ ={0.995}-0.047+0.037 under th…
An X-Ray Periodicity of ∼1.8 hr in Narrow-line Seyfert 1 Galaxy Mrk 766
Zhang, Peng; Zhang, Peng-fei; Yan, Jing-zhi +2 more
In the narrow-line Seyfert 1 galaxy Mrk 766, a quasi-periodic oscillation (QPO) signal with a period of ∼6450 s is detected in the XMM-Newton data collected on 2005 May 31. This QPO signal is highly statistically significant at the ∼5σ confidence level, with a quality factor of Q=f/{{Δ }}f> 13.6. The X-ray intensity changed by a factor of 3, wi…
Mapping the Extinction Curve in 3D: Structure on Kiloparsec Scales
Peek, J. E. G.; Schlafly, E. F.; Finkbeiner, D. P. +1 more
Near-infrared spectroscopy from APOGEE and wide-field optical photometry from Pan-STARRS1 have recently made precise measurements of the shape of the extinction curve possible for tens of thousands of stars, parameterized by R(V). These measurements revealed structures in R(V) with large angular scales, which are challenging to explain in existing…
UVUDF: UV Luminosity Functions at the Cosmic High Noon
Gardner, Jonathan P.; Teplitz, Harry I.; Scarlata, Claudia +14 more
We present the rest-1500 Å UV luminosity functions (LF) for star-forming galaxies during the cosmic high noon—the peak of cosmic star formation rate at 1.5< z< 3. We use deep NUV imaging data obtained as part of the Hubble Ultra-Violet Ultra Deep Field (UVUDF) program, along with existing deep optical and NIR coverage on the HUDF. We select …
An Imperfectly Passive Nature: Bright Submillimeter Emission from Dust-obscured Star Formation in the z = 3.717 “Passive” System, ZF 20115
Ivison, R. J.; Smail, Ian; Dunlop, J. S. +28 more
The identification of high-redshift, massive galaxies with old stellar populations may pose challenges to some models of galaxy formation. However, to securely classify a galaxy as quiescent, it is necessary to exclude significant ongoing star formation, something that can be challenging to achieve at high redshifts. In this Letter, we analyze dee…
Characteristics of Solar Energetic Ions as a Function of Longitude
Cohen, C. M. S.; Mewaldt, R. A.; Mason, G. M.
Since the 2006 launch of STEREO, multi-spacecraft studies have yielded several surprising results regarding the spread of solar energetic particles (SEPs) within the inner heliosphere. We have investigated the role of energy and ridigity, using ACE and STEREO 10 MeV n-1 oxygen data to identify 41 large SEP events observed by two or thre…
CO-driven Activity in Comet C/2017 K2 (PANSTARRS)
Chambers, Kenneth C.; Magnier, Eugene; Bauer, James +12 more
Comet C/2017 K2 (PANSTARRS) was discovered by the Pan-STARRS1 (PS1) Survey on 2017 May 21 at a distance of 16.09 au from the Sun, the second most distant discovery of an active comet. Pre-discovery images in the PS1 archive back to 2014 and additional deep CFHT images between 2013 May 10-13 showed the comet to be active at 23.75 au. We derive an u…
Discovery of Extended Main-sequence Turnoffs in Four Young Massive Clusters in the Magellanic Clouds
Milone, Antonino P.; Deng, Licai; de Grijs, Richard +1 more
An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are popu…
What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?
Martínez-Sykora, Juan; De Pontieu, Bart; Chintzoglou, Georgios
Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100-300 km s-1 in spicules, as measured in the plane of the s…